1. Field of the Invention
The present application relates to a semiconductor stacking layer and a fabricating method thereof. More particularly, the present application relates to a semiconductor stacking layer composed of an amorphous silicon (a-Si) layer and a microcrystalline silicon (μc-Si) layer and a fabricating method of the semiconductor stacking layer.
2. Description of Related Art
In recent years, due to the mature optoelectronic technology and the advanced semiconductor fabrication technology, flat panel displays are developed rapidly. Among the flat panel displays, thin film transistor liquid crystal displays (TFT-LCDs) having advantages of low operation voltage, fast response speed, light weight, and compactness have become mainstream of displays on the market.
A conventional TFT includes a substrate, a gate, a gate insulation layer, a semiconductor layer, an ohmic contact layer, a source, and a drain. The gate is disposed on the substrate, and the gate insulation layer is disposed on the substrate and covers the gate. The semiconductor layer is disposed on the gate insulation layer and located above the gate. The ohmic contact layer is disposed on a portion of the semiconductor layer, and the source and the drain are disposed on the ohmic contact layer. When a turn-on voltage is input to the gate, the semiconductor layer becomes conductive, and thus the source and the drain can be conducted through the semiconductor layer.
In general, the semiconductor layer in the TFT is mainly composed of a channel layer and an ohmic contact layer. A material of the channel layer is un-doped a-Si or lightly doped a-Si, and a material of the ohmic contact layer is n-type heavily doped a-Si or n-type heavily doped μc-Si. Compared to the a-Si material, μc-Si has better doping efficiency and lower resistivity due to the material and structural properties of μc-Si. Therefore, μc-Si has been gradually applied to fabrication of the ohmic contact layer. Nonetheless, when μc-Si is applied to fabrication of TFTs or other semiconductor devices, there exist defects on interfaces between μc-Si and other thin films because of the difference between the properties of μc-Si and those of the thin films. These defects adversely affect characteristics of the semiconductor devices.
Therefore, during fabrication of the semiconductor devices, it is rather imperative to remove or reduce the interface defects existing between μc-Si and other thin films.